In the present computer-related industrial fields, a passive-type heat sink is usually tightly attached to a heat-producing surface of an electronic element, such as a central processing unit (CPU), a south and north chip set, etc., so that the produced heat can be effectively carried away from the electronic element to dissipate into ambient air, ensuring the heat-producing electronic element to operate at a proper working temperature.
Conventionally available heat sinks can be generally divided into two types, namely an integral heat sink and an assembled heat sink. The integral heat sink mainly has a base, one side of which is in direct contact with a heat source and the other side of which is formed into a plurality of outward extended radiating fins for radiating heat absorbed by the base into ambient air. The assembled heat sink 1, as shown in FIGS. 1A and 1B, includes a base 10 and a plurality of radiating fins 12 assembled to the base 10. The base 10 is formed with a plurality of slots 101 sunken into an upper side of the base 10 for the radiating fins 12 to correspondingly insert therein. A lower side of the base 10 is in contact with a heat-producing element 14, such as a CPU or a south and north bridge chipset, for absorbing the heat produced by the heat-producing element 14.
Each of the radiating fins 12 has a heat-absorption end 121 and a heat-dissipation end 122 extended from the heat-absorption end 121. The heat-absorption ends 121 of the radiating fins 12 are correspondingly held in the slots 101, so that the base 10 and the radiating fins 12 together form the heat sink 1. When the heat-producing element 14 produces heat, the base 10 absorbs the produced heat and guides the absorbed heat to the heat-absorption ends 121 correspondingly held in the slots 101, and then the heat-absorption ends 121 further transfer the received heat to the heat-dissipation ends 122, from where the heat is radiated into ambient air and diffused.
While the two types of conventional heat sinks all can achieve the purpose of carrying heat away from the heat-producing element 14, they do not provide good heat dissipation effect. This is because the heat produced by the heat-producing element 14 is first transferred to the base 10 and then indirectly transferred to the radiating fins 12 via the base 10. Thermal resistance tends to occur during the process of transferring the heat from the base 10 to the radiating fins 12 to thereby result in lowered heat transfer efficiency and accordingly poor heat dissipation effect.
In conclusion, the conventional heat sinks have the following disadvantages: (1) having low heat transfer efficiency; (2) indirect heat transfer from the heat source via the base to the radiating fins causing the problem of thermal resistance; and (3) providing poor heat dissipation effect.
It is therefore tried by the inventor to develop an improved thermal module that eliminates the drawbacks in the conventional heat sinks to provide upgraded heat transfer efficiency and excellent heat dissipation effect.